Patent attributes
In order to allow the use of an ink jet printing head of drop-on-demand type and with an ink nozzle assembly having a predetermined length in a direction of travel of a paper web to perform high precision and high speed printing, the ink jet printing head (2) is disposed relative to the traveling paper web (4) at a position such that the nozzle assembly (2a) lies opposed to a linearly traveling surface area of paper web that is leaving from a guide roller (3) immediately after the traveling paper web has had its wrapping contact with the same or a linearly traveling surface area of paper web that is approaching a guide roller (3) immediately before the traveling paper web has its wrapping contact with the same. The nozzle assembly (2a) of the ink jet printing head (2) has its upstream end positioned to coincide in position with a paper wrap end point lying at a downstream end of a paper wrap region in which the paper web (4) is wrapped on the guide roller (3) or has its downstream end positioned to coincide in position with a paper wrap start point lying at a upstream end of a paper wrap region in which the paper web (4) is wrapped on the guide roller (3).
